Light-based treatment of tissue is used for a variety of applications, such as hair removal, skin rejuvenation, wrinkle treatment, acne treatment, treatment of vascular lesions (e.g., spider veins, diffuse redness, etc.), treatment of cellulite, treatment of pigmented legions (e.g., age spots, sun spots, moles, etc.), tattoo removal, and various other treatments. Such treatments generally include delivering light or laser radiation to an area of tissue on a person's body, e.g., the skin or internal tissue, to treat the tissue in a photochemical, photobiological, thermal, or other manner, which can be ablative or non-ablative, among other properties, depending on the particular application. Light-based treatment devices include various types of radiation sources, such as lasers, LEDs, flashlamps, etc. For example, laser diodes are particularly suitable for certain light-based treatments and devices for providing such treatments.
One shortcoming of skin care routines practiced at home, including light-based treatments using home consumer devices, is the inability to objectively visualize or analyze the efficacy of a treatment over time, particularly where the results of the treatment are gradual over a period of weeks or even months. Light-based skin treatments using home consumer devices typically routines have slow and small incremental changes that can only be observed over a period of weeks or months. The only feedback that most people get is their daily look on their mirrors or their own tactile sensation. The relative results are difficult to assess, especially when previous reference is based on memory. Thus, users may become discouraged by the lack of objective feedback, and may thus prematurely terminate a treatment regimen.